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31.
32.
Lothar Dresen Stefan Freystätter Jan Kozák Ivan Pšenčík Reviewer V. Červený 《Studia Geophysica et Geodaetica》1977,21(2):137-142
Summary The space (time) delay of transmitted waves in the vicinity of the interface beyond the critical point is investigated on two-dimensional seismic models of a low velocity channel; results of laboratory experiments are compared with the conclusions of the theory. The effect of the time delay in field measurements is demonstrated by means of two typical geological formations. 相似文献
33.
34.
Prof. Dr. Lothar Geitler 《Aquatic Sciences - Research Across Boundaries》1968,30(1):186-187
Zusammenfassung Die Argumente, dieAnagnostidis undRathsack-Künzenbach zugunsten der Blaualgennatur von ?Isocystis pallida? anführen, sind hinf?llig, weil die Fortpflanzung obligat durch Knospung nach Art der Hefepilze, nicht durch Zweiteilung
erfolgt, also die Pflanze grunds?tzlich anders als Blaualgen organisiert ist.
Summary ‘Isocystis pallida’ is not a blue green alga, arguments against this statement expressed byAnagnostidis andRathsack-Künzenbach are not valid. In view of the obligatory budding of the cells, in manner of yeasts, instead of binary fission, the organism must be considered as a species of the genusTorulopsidosira.相似文献
35.
Oxygen isotopes in single micrometer-sized quartz grains: tracing the source of Saharan dust over long-distance atmospheric transport 总被引:1,自引:0,他引:1
Jérôme Aléon Marc ChaussidonBernard Marty Lothar SchützRuprecht Jaenicke 《Geochimica et cosmochimica acta》2002,66(19):3351-3365
Oxygen isotope compositions were measured by ion microprobe in individual micrometer-sized quartz grains extracted from one aerosol sample collected on the Cape Verde Islands and from four surface samples (three soils and one sediment) representing potential source regions of aerosols in Western and Central Africa (Morocco, Algeria, Niger, and Chad). A large range of δ18O values, from +6.2‰ to +39.3‰ is present within the aerosol quartz grains. The different size fractions of the quartz grains from the surface samples overlap nearly entirely this range but show significant differences in their δ18O distributions for the different size fractions of the grains (i.e., different modes, different proportions of grains with low or high δ18O, ...). These differences in δ18O distributions can be related to different geological formations (i.e., mantle-derived magmatic rocks, crustal magmatic rocks, or sedimentary rocks) outcropping in each region, thus giving a fingerprint of the source region. Quartz grains with unusually high δ18O values between +30‰ and +40‰ were attributed to lacustrine cherts formed in evaporitic environments (Chad basin).The existence of distinct δ18O distributions for the surface samples, which reflect regional geology but indicate some transport of the grains, enables the characterization of mixing processes during dust emission in the atmosphere. Particles are mixed at a regional scale in the dust reservoir, but injection of fine particles into the high troposphere occurs as a discrete and localized event with no mixing during the subsequent long-range transport by the easterlies. The comparison of the δ18O distribution of the quartz from the aerosol sample with the equivalent size fractions in surface samples shows that the Niger area is the more probable source region for the aerosol although the Moroccan source cannot be excluded. This method gives a valuable tool to trace the source region of dust into the atmosphere or into sediment samples, allowing the reconstruction of air mass circulations. 相似文献
36.
Lothar Ratschbacher Christian Dingeldey Christine Miller Bradley R. Hacker Michael O. McWilliams 《Tectonophysics》2004,394(3-4):155-170
New 40Ar/39Ar geochronology places time constraints on several stages of the evolution of the Penninic realm in the Eastern Alps. A 186±2 Ma age for seafloor hydrothermal metamorphic biotite from the Reckner Ophiolite Complex of the Pennine–Austroalpine transition suggests that Penninic ocean spreading occurred in the Eastern Alps as early as the Toarcian (late Early Jurassic). A 57±3 Ma amphibole from the Penninic subduction–accretion Rechnitz Complex dates high-pressure metamorphism and records a snapshot in the evolution of the Penninic accretionary wedge. High-pressure amphibole, phengite, and phengite+paragonite mixtures from the Penninic Eclogite Zone of the Tauern Window document exhumation through ≤15 kbar and >500 °C at 42 Ma to 10 kbar and 400 °C at 39 Ma. The Tauern Eclogite Zone pressure–temperature path shows isothermal decompression at mantle depths and rapid cooling in the crust, suggesting rapid exhumation. Assuming exhumation rates slower or equal to high-pressure–ultrahigh-pressure terrains in the Western Alps, Tauern Eclogite Zone peak pressures were reached not long before our high-pressure amphibole age, probably at ≤45 Ma, in accordance with dates from the Western Alps. A late-stage thermal overprint, common to the entire Penninic thrust system, occurred within the Tauern Eclogite Zone rocks at 35 Ma. The high-pressure peak and switch from burial to exhumation of the Tauern Eclogite Zone is likely to date slab breakoff in the Alpine orogen. This is in contrast to the long-lasting and foreland-propagating Franciscan-style subduction–accretion processes that are recorded in the Rechnitz Complex. 相似文献
37.
Bernhard M. Krooss Lothar Friberg Yves Gensterblum Jan Hollenstein Dirk Prinz Ralf Littke 《International Journal of Earth Sciences》2005,94(5-6):1023-1038
Open-system non-isothermal pyrolysis up to 1,200°C in combination with elemental analysis was used to study the thermal liberation
of molecular nitrogen (N2) from sedimentary rocks and kerogen concentrates of Palaeozoic age from the Central European Basin system and an Eocene shale
(Liaohe Basin, China) with a high content (36%) of ammonium feldspar (buddingtonite). The N/Corg (atomic) ratios of the kerogen concentrates ranged from 0.005 to 0.014, which represents the range commonly observed for
coals. Bulk N/Corg ratios of the Palaeozoic shales extended from 0.035 to 0.108, indicating the presence of significant amounts of inorganic
nitrogen. Namurian A and A-B (CnA; CnA-B) samples typically exhibited the earliest onset of N2 generation with intense, characteristic peaks around 600°C. N2 liberation from the buddingtonite-rich sample occurred at higher temperatures, with a broad peak around 700°C. Pyrograms
of the kerogen concentrates showed no or strongly reduced N2 generation in the 500–700°C range. On-line isotope-specific analysis of the pyrolytically liberated N2 on one sample revealed a variability of ∼10‰ in the δ15N values and a steady increase in δ15N with temperature during the main phase of N2 generation. 相似文献
38.
The rainwater composition in the vicinity of Mainz, FRG, has been investigated with special emphasis on insoluble constituents. The number size distribution was determined in the range from 0.1 m up to 100 m radius. For particles with r>0.5 m radius the shape of the size distribution of insoluble particles in rain follows the shape of the average urban and rural aerosol. In this particular size range no major size selective removal processes could be seen. For r<0.5 m the number size distribution tends to flatten compared to the average aerosol. This might be the indication of a size selective removal process (Greenfield Gap). 相似文献
39.
Sandra M. Richwalski Andreas Fäcke Stefano Parolai Lothar Stempniewski 《Natural Hazards》2006,38(1-2):237-246
An overlap in frequency between the 1D resonance frequency of sediments and the vibrational frequencies of long-span bridges
might lead to a strongly increased structural response of the latter. Interference of surface waves caused by reflections
at dipping interfaces may introduce additional unfavourable amplifications. Therefore, the vulnerability of two bridges crossing
the Rhine River in Cologne, Germany, was assessed using ground motion scenarios computed for four profiles crossing the Lower
Rhine Embayment. Due to their vibrational frequencies being in the vicinity of resonant peaks in the response spectra, the
Severinsbridge showed critical loading and the bridge Cologne-Deutz even exhibited grave failure according to the dynamic
FE-simulations. 相似文献
40.